1. Field of the Invention
The present invention generally relates to a liquid crystal display device, and more particularly, to a light shielding construction for protecting a thin film transistor against light projected onto a liquid crystal display panel to prevent deterioration of characteristics of the projection type liquid crystal display device using the thin film transistor, or of a transmission type liquid crystal display device with back-light illumination employing the thin film transistor means.
2. Description of the Background Art
In FIGS. 12 to 15, there is shown one example of a conventional liquid crystal display device employing a thin film transistor (referred to as a TFT-LCD hereinafter).
As shown in FIGS. 12 and 13, the thin film transistor liquid crystal display panel P (referred to as a TFT-LCD panel hereinafter) employed in the TFT-LCD includes a TFT array substrate TB formed with a TFT array TFT and a transparent display electrode DE, a counter substrate CE formed with a light shielding film SH for preventing light of a light source from entering the TFT and a transparent counter electrode, and a liquid crystal layer contained in a space between the substrates CE and TB bonded to each other by a sealing resin RE as illustrated.
As shown in FIG. 13, electrode terminals GE of gate electrode lines and electrode terminals SE of source electrode lines led out from an image area are provided on a peripheral portion of the TFT substrate TB.
For applying electrical signals to the above lines from a driving circuit (not particularly shown), flexible substrate FS-1, FS-2, and FS-3 mounted thereon with large scale integrated (LSI) circuits LS-1, LS-2 and LS-3 are connected to said electrode terminals GE and SE. Moreover, the connected portion between the flexible substrates LS-1 to LS-3 and the TFT substrate TB is covered by a white silicon mold resin RM for protecting the connected portion, and thus, a TFT-LCD unit is formed.
In FIG. 14 in which wiring patterns of the flexible substrates FS-1 to FS-3 are schematically shown for clarity, a frame FR formed with fixing holes h at its four corners is attached to the TFT-LCD panel P. Conventionally, such a TFT-LCD unit as described above is mounted on a projection optical system so as to be used as a projection type liquid crystal display device.
Commonly, a TFT-LCD employs a twisted nematic mode, with polarizing plates (not shown) disposed before and after the TFT-LCD panel. It has been clarified by the study of the present inventors, that in the above case, better display characteristics may be obtained when light from the light source is incident upon the TFT-LCD panel from the side of its confronting substrate.
However, when the optical system as described above is adopted, there has been such a disadvantage that, due to the fact that the mold resin RM for protecting the connected portion between the flexible substrates FS-1 to FS-3 and the TFT substrate TB referred to FIG. 14 is in conventionally, light La from the light source L incident upon the mold resin RM is scattered within said resin. The scattered light enters the interior of the TFT-LCD panel to be incident upon the TFT as indicated by arrows in FIG. 15, and by this scattered light, photo-conduction is generated in a semi-conductor film of the TFT, resulting in deterioration of switching characteristics of the TFT due to the light scattered by in the mold resin.